Abundance of elements in Earth's crust
The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million by mass - the mass fraction of the element in the earth's crust, multiplied by the mass of the earth's crust. Note that the noble gases are not included, as they form no part of the solid crust. Also not included are certain elements with extremely low crustal concentrations: technetium, promethium, and all elements with atomic numbers greater than 83 except thorium and uranium.
Estimates of elemental abundance are difficult because the composition of the upper and lower crust are quite different, and the composition of the continental crust can vary drastically by locality.
